Air heater



FIG. 1 is a left side elevational view of the air heater showing our design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a front perspective view thereof.

The broken lines in FIGS. 4 and 5 show portions of the air heater that form no part of the claimed design. 

CLAIM The ornamental design for an air heater, as shown and described. 